The present invention relates to a single lens reflex camera on which a taking lens unit and a camera back are detachably mounted, and more particularly relates to a single lens reflex camera with a reflex mirror which is controlled by a mirror controller to move between a viewing position wherein the reflex mirror is disposed in the photographic light path and a photographing position wherein the reflex mirror is out of the photographic light path.
As commercial or semiprofessional single lens reflex cameras of the type having a large format, various single lens reflex cameras having lens-shutter assemblies are well known in the art. One such type of single lens reflex camera generally comprises a camera body, a taking lens unit incorporating a lens-shutter assembly detachably mounted on the camera body, and a film magazine or camera back also detachably mounted on the camera body. Some of these large format single lens reflex cameras are adapted to swing and tilt by the aid of a bellows connected between the taking lens unit and the camera body.
Single lens reflex cameras have a swingable reflex mirror for reflecting light from a subject to a focusing screen of a viewing system. The reflex mirror is adapted to swing up to a photographing position wherein the reflex mirror is out of the photographic light path of the camera to allow a film in the camera to be exposed to the light passing through the taking lens. In such a large format single lens reflex camera, because the shutter is open when the reflex mirror is in the viewing position, it is necessary to provide the camera body with a light-blocking plate which is swingable up and down in cooperation with the mirror and isolates the film in the camera from any light in the viewing position.
As the reflex mirror of a single lens reflex camera is adapted to swing up rapidly immediately before an exposure is made, vibrations are produced in the camera. These vibrations detract from the quality of the photographed images, in particular images photographed under extreme conditions. Another problem in such single lens reflex cameras is that the reflex mirror interferes with some kinds of lenses, for example by having long back flanges where they are attached to the camera. To avoid these problems, such a single lens reflex camera can be provided with a manually operable mirror swing-up device which swings up and holds the reflex mirror in the photographing position, independently from ordinary photographic sequential operations.
The single lens reflex camera of the type having a lens-shutter assembly generally has the problem that because of the lens-shutter assembly, the film will be accidentally exposed to light when the reflex mirror and light-blocking plate are moved up to the photographic position with the taking lens detached from the camera.
To avoid this problem, the reflex mirror and light-blocking plate can be arranged to be moved to the viewing position if the taking lens is detached from the camera. In this way, accidental exposure can be reliably prevented when exchanging taking lenses. However, this is made possible only by using specially made interchangeable taking lenses. For this reason, the camera cannot use lenses which are not systematized, such as lenses having large flange backs, and the camera is impossible to demonstrate by swinging up and down the reflex mirror with no taking lens mounted thereon.